Excessive gestational weight gain (EGWG) is disproportionally prevalent in overweight or obese pregnant women (65-85%). EGWG has detrimental effects on maternal and birth outcomes, e.g., gestational diabetes, gestational hypertension, cesarean delivery, and fetal macrosomia. EGWG is preventable through healthy eating and physical activity (healthy lifestyle behaviors). Current effective lifestyle behavior intervention studies aimed to prevent EGWG in overweight or obese pregnant women have limited practicality, scalability, and sustainability because of high participant burden and excessive cost for clinical practice. Also, prior studies paid little or no attention to motivation, emotion and cognition, all of which are critical to motivate and enable individuals to engage in healthy lifestyle behaviors and achieve positive health outcomes. A promising approach to prevent EGWG in overweight or obese pregnant women is through goal-oriented episodic future thinking (GOEFT). The proposed R21, a pilot randomized controlled trial, aims to prevent EGWG in overweight or obese pregnant women. The proposed self-directed, web-based GOEFT intervention will focus on increasing motivation (autonomous motivation and self-efficacy) and improving emotion (emotion control and stress) and cognition (executive function, ExF), thus promoting healthy lifestyle behaviors leading to prevention of EGWG (primary outcome) and a reduced rate of gestational diabetes, gestational hypertension, cesarean delivery and fetal macrosomia (secondary outcomes). Our intervention will last 20 weeks (starting ?15 week- gestation). Via a self-directed, web-based GOEFT intervention, participants will engage in weekly intervention activity (35-40 min/week). Participants (N = 90; 50% White, 50% minority) will be recruited and enrolled from prenatal care clinics at The Ohio State University Wexner Medical Center and be randomly assigned to our GOEFT intervention (n = 45) or usual care (n = 45). All participants will be assessed at baseline (?15 week- gestation, T1), 24-27 week-gestation (T2) and 35-37 week-gestation (T3). Specific aims are (1) to determine feasibility of the GOEFT intervention: recruitment, randomization, retention and intervention implementation, (2) to investigate the potential efficacy of the intervention on gestational weight gain and maternal and birth outcomes, (3) to investigate the potential impact of the intervention on lifestyle behaviors and (4) to investigate the potential impact of the intervention on motivation, emotion and cognition. Innovation. This is the first lifestyle behavior intervention aimed to prevent EGWG that applies GOEFT to increase motivation, emotion, ExF and healthy lifestyle behaviors. Significance. The study findings will provide important implications for designing a lifestyle behavior intervention to prevent EGWG in overweight or obese pregnant women. If successful, the GOEFT intervention could be tested in a large scale randomized controlled trial to determine efficacy and potential for long-term weight maintenance.